The oil filter light is on in your 2004 Toyota Highlander why?

To answer the Maint REOD question that was linked to this one.

The Maint REOD is a "Reminder" that is based only on the current mileage on the vehicle. It "Goes Off" every 5 thousand miles. if you want to reset it.

Make sure your Odometer is set to the ODO mode, not one of the trip counters.

Turn the vehicle all the way off

Hold the Odomoter reset button

Turn the vehicle on to Accessory Mode while holding the button.

you should see a series of dots cross the ODO display.